Mixer tap for a sink



FIG. 1 is a perspective view of the top, front and right side of a mixer tap for a sink showing our new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a left side view thereof; and,

FIG. 4 is a top plan view thereof. 

The ornamental design for a mixer tap for a sink, as shown. 